GB1568342A

GB1568342A - Process for the production of hot gas by preparing a gasiform hydrocarbon fuel from hydrocarbon fuel oil and burning the fuel

Info

Publication number: GB1568342A
Application number: GB1317/78A
Authority: GB
Original assignee: Allied Chemical and Dye Corp; Allied Chemical Corp
Current assignee: Allied Corp
Priority date: 1977-01-13
Filing date: 1978-01-12
Publication date: 1980-05-29
Also published as: IT7867014A0; DE2800834A1; JPS5388004A; NL7714557A; IT1156404B

Description

(54) PROCESS FOR THE PRODUCTION OF HOT GAS BY PREPARING A GASIFORM HYDROCARBON FUEL FROM HYDROCARBON FUEL OIL AND BURNING THE FUEL (71) We, ALLIED CHEMICAL CORPORATION, a Corporation organised and existing under the laws of the State of New York, United States of America, of Columbia Road, and Park Avenue, Morris Township, Morris County, New Jersey 07961, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the production of a hot gas obtained by burning a gasiform hydrocarbon fuel, and is an improvement in or modification of the invention described in our British Patent Application No.

5805/76 (Serial No. 1,532,261).

In view of the limited world resources of natural gas, it is imperative that alternative sources of low-cost gaseous heating fuels be developed.

U.S. Patent 3,561,895 to H.D. Michelson is directed to a method for control of fuel gas combustion. Inspirated air to inspirating type burners is maintained constant when one vapor fuel, e.g., natural gas, is changed for another, by heating or cooling the fuel in response to density variation, and supplementally by adding enriching or diluting gases. Preferred fuels for said method are light hydrocarbons; however, such fuels are not economic for use in industrial furnaces, as compared with natural gas or fuel oils.

It has long been known to pyrolyze and/or partially oxidize hydrocarbon fuel oils into a high heating value "oil gas" or into low heating value gas containing carbon monoxide and nitrogen. However, neither of these gases is interchangeable with natural gas. More recently, patents have issued on methods for preparing from hydrocarbon oils, or residuals, a fuel gas which has essentially the same heating value as natural gas.

U.S. Patent 3,712,800 to A. H. Schutte discloses converting residual oils into a fuel gas having a heating value of about 950 to 1,000 B.T.U. per standard cubic foot. The residual oil containing one or more metallic modifiers as catalysts (which may be naturally occurring in the oil or added thereto) is pyrolyzed in the presence of a small amount of steam at 1,000 to 1,4000F.

and pressures of 5 to 30 psig., and from the products of the pyrolysis of fuel gas is separated. This fuel gas is a mixture of methane, hydrogen and ethane/ethylene.

U.S. Patent 3,784,364 to W. L. Slater et al.

discloses production of fuel gas having a heating value between 150 and 1,000 B.T.U.

per standard cubic foot. The gas is prepared by subjecting a hydrocarbon oil to partial combustion at a temperature of about 1,300 to 1,6000F. using air as the oxidizing medium and injecting additional hydrocarbon oil into the hot partial combustion products.

U.S. Patent 3,838,994 to C. L. Aldridge discloses conversion of heavy hydrocarbons to a methane rich gas product by contact with steam in the presence of a non-molten particulate alkali metal containing catalyst at pressures greater than 200 psig. and average temperatures between 1,000 and 1,500 F. An oxygen-containing gas may be introduced into the reaction mixture to provide a portion of the heat requirement.

U.S. Patent 3,928,800 to E. T. Child et al.

is directed to production of a methane-rich fuel gas from high-sulfur hydrocarbonaceous fuel. The high sulfur hydrocarbonaceous fuel is gasified by partial oxidation with substantially pure oxygen at about 1,700 to 3,100 F. and a pressure of 1 to 250 atmospheres to produce a process gas stream which is cooled, cleaned and subjected to catalytic methanation over a sulfur-resistant catalyst.

In prior processes for production of gaseous fuels involving pyrolysis and/or partial oxidation of hydrocarbon oil at temperatures of l,000 F. or higher, from about 0.1 to about 10 weight percent, based on the hydrocarbon feed, of entrained particulate carbon is produced due to cracking of the hydrocarbon oil. Solid carbonaceous deposits from downstream from the reaction zone on the surfaces of vessels, lines, and heat exchangers. This entrained particulate carbon may be separated and recovered from the gas stream by known scrubbing and extraction processes but disadvantages of carbon recovery processes include the high cost of equipment and materials, and the operation of said recovery processes. Therefore, it would be desirable to provide a process which eliminates cracking of the hydrocarbon fuel oil to form entrained particulate carbon.Clearly, such process should avoid the prior art pyrolysis and/or partial oxidation of the hydrocarbon fuel oil.

The present invention provides a process of producing a hot gas, which process comprises preparing a gasiform fuel by vaporizing a portion of a liquid hydrocarbon fuel oil having a gravity of 10 to 50 degrees A.P.I. at a temperature of 350 to 675at in the presence of 5 to 90% by weight of a non oxidizing inert gas (as hereinafter defined), based on the weight of the vaporized portion of said hydrocarbon fuel oil, separating the resulting gasiform fuel from the liquid phase, and burning the gasiform fuel in a burner equipped to burn gasiform hydrocarbon fuel.

In the process of the invention the vaporized fuel oil is diluted with a non oxidizing, inert, carrier gas. Under the conditions of the process, the gas is inert in that it does not enter into any chemical reaction, with the hydrocarbons or any other gas with which it may come into contact, of a kind which reduces the fuel value of the product gas to be burnt in the burner. In particular, it is non-oxidizng in that it does not cause oxidation of the hydrocarbons under the process conditions.

Preferably also it should be non-sulfur bearing and if possible in other respects substantially free from substances which would produce a combusted gas containing atmospheric pollutants.

In our above-mentioned earlier British Patent Application No. 1,532,261 we have described and claimed a similar process in which the non-oxidizing gas is steam, or a mixture of steam and natural gas, but in which the portion of liquid hydrocarbon fuel vaporised is defined as at least 25% by weight. The term "non-oxidizing gas" in the context of the present invention therefore excludes steam and a mixture of steam and natural gas when the portion of fuel oil vaporized is 25% by weight or more.

Preferably the non-oxidizing, inert gas is natural gas. However, many different kinds of gas are usable, for example the "purge gas from ammonia synthesis. The purge gas is obtained by purging an accumulation of non-reactive gases from the ammonia synthesis feedline with ammonia gas. It generally comprises hydrogen, argon, nitrogen and ammonia. A mixture of steam and non-oxidizing gas, which may be a nonoxidizing gas other than natural gas, for example ammonia synthesis purge gas, may also be employed.

A valuable effect of using the nonoxidizing gas is the reduction of vapor pressure of the fuel oil vapor, thereby enabling the vaporizion to be carried out at a relatively low temperature.

The process of the present invention is an economical process for producing and burning a gasiform hydrocarbon fuel. The fuel can be used in place of natural gas if the burners are suitable. Many industrial furnaces have burners designed for burning natural gas, and these burners are generally suitable.

The gasiform hydrocarbon fuel prepared in the process of the invention is normally substantially free from entrained particulate carbon.

By a process of the invention it is possible, subject of course to a sensible choice of non-oxidizing, inert gas, to produce from a hydrocarbon fuel oil containing pollutant and corrosive impurities, a clean gasiform hydrocarbon fuel and to burn it in industrial furnaces without corrosion, soot, slagging or pollution problems.

The invention also includes in particular a process for the production of synthesis gas (comprising carbon monoxide and hydrogen), which comprises reacting a gasiform hydrocarbon with steam at a temperature of at least 1200"F in a reforming reaction for conversion of the hydrocarbon and steam directly into carbon monoxide and hydrogen, and supplying heat to said reforming reaction from hot gas produced by the above defined process of the invention. It is especially useful where the hot gas from the burner is contacted with a stainless steel furnace in heat-supply relationship to the reforming reaction.

Except in unusual and relatively unimportant circumstances, the only commercial liquid fuels sufficiently cheap for use in the present invention are certain fractions of petroleum oil. Accordingly, the term hydrocarbon fuel oil or fuel oil, as used herein will refer to these materials only.

The petroleum refiner uses crude oil as his raw material. This material consists of a series of hydrocarbons varying from dissolved gases to heavy, nearly solid compounds. Certain fractions of this crude petroleum which may be separated by simple distillation will have the necessary properties for use as fuel oil. The petroleum refiner also practices forms of destructive distillation which are called either thermal or catalytic cracking. In these processes some hydrocarbons suitable for fuel oil are also produced. Fuel oils as received from the refiner may not be homogenous and may contain considerable water and salts in suspension.

In addition to sulfur, many fuel oils contain trace quantities of mineral impurities such as vanadium, sodium, calcium, magnesium and iron. If such oil is burned in a furnace having steel tubes, e.g., a reformer furnace, even with the best metallurgy available, the vanadium oxides will attack the tubes resulting in rapid failure from pitting attack. In cases where sodium is present, sodium oxides formed on combustion of the fuel oil dissolve or "flux" the protective oxide film on the tubes, thereby greatly accelerating attack by the aforementioned vanadium oxides. Further, in heat recovery operations, these minerals fuse on heat recovery surfaces, forming deposits which retard heat transfer and increase rate of soot formation. It is therefore an important contribution to this art that the present invention overcomes these problems.

In accordance with the present invention the gravity of the hydrocarbon fuel oil in terms of degrees A.P.I. is determined.

Determination can be made by a hydrometer graduated in terms of specific gravity, but it is preferably made with a hydrometer carrying an arbitrary scale termed "Degrees A.P.I.". The latter is defined by: 141.5 Degrees A.P.I.= -131.5 specific gravity 60 F./60 F.

In making tests, it is advisable to refer to Petroleum Products and Lubricants, Am.

Soc. Testing Materials Rept. Comm. D2.

This report is issued annually and contains standard methods for determination.

The accompanying drawing diagrammatically illustrates one method of carrying out the operation of the present invention.

The preferred process of this invention may be stated as follows: A process for preparing a gasiform hydrocarbon fuel from a hydrocarbon fuel oil, and maintaining same in such form into a gasiform burner, which comprises: (a) partially vaporizing about 25-75 percent by weight of a liquid hydrocarbon fuel oil having a gravity of about 30-40 degrees A.P.I. at a temperature of 350- 675"F. in the presence of 8-30 percent by weight of non-oxidising gas, based on the weight of the vaporized portion of said hydrocarbon fuel oil, thereby producing a gasiform hydrocarbon fuel and a liquid residue, said gasiform hydrocarbon fuel consisting essentially of said vaporized liquid hydrocarbon and said non-oxidizing gas:: (b) separating said gasiform hydrocarbon from said liquid residue; (c) superheating said gasiform fuel to maintain said gasiform fuel in the vapor state until it is burned, and (d) thereafter burning said gasiform fuel in said gasiform burner.

In one of its more specific aspects, the present invention is concerned with the production of a gasiform fuel suitable for burning in reforming furnaces used for the manufacture of synthesis gas, e.g. feed gas for the synthesis of ammonia.

The synthesis of ammonia from hydrocarbons, steam and air has become of increasing importance in recent years.

Natural gas is generally used as the hydrocarbon from which hydrogen is generated for the ammonia synthesis reaction. In the usual commercial process, natural gas, after treatment for removal of sulfur compounds, is mixed with steam and passed over a nickel oxide catalyst at a temperature of about 1,2001,600 F, in externally heated furnace tubes known as the primary reformer. The heated furnace tubes are normally heated by means of burners equipped to burn natural gas. The principal reactions occurring in the primary reformer are: CH4+H2OeC0+3H2 CO+H2OCO2+H2 In the conventional commercial process, the effluent gas from the primary reformer is mixed with air in amount sufficient to supply the nitrogen required in the subsequent ammonia synthesis.The resulting mixture is supplied to a secondary reformer containing nickel oxide as catalyst.

In the secondary reformer, oxygen from the air combines with a portion of the hydrogen, producing water vapor and nitrogen: Air (N2+O2)+2H2 < N2+2H2O Carbon oxides are present in the effluent from the secondary reformer, and the effluent is treated for the removal of both carbon monoxide and carbon dioxide to obtain relatively pure hydrogen and nitrogen as ammonia synthesis feed gas.

To produce ammonia, the purified gas is compressed to the desired reaction pressure, e.g. 5,000 psig. and passed at a suitable reaction temperature, e.g. 9500 F., over an ammonia synthesis catalyst, e,g.

magnetic iron oxide promoted with potassium and aluminum oxides and subsequently reduced to metallic iron.

The availability of large natural gas reserves coupled with development of the above-described hydrogen manufacture via high-temperature catalytic steam reforming of hydrocarbons has led to a situation where almost all domestic ammonia and hydrogendependent products are manufactured in plants fed and fueled by natural gas.

However, with diminishing reserves of natural gas, it is advisable to look toward conversion of existing plants from natural gas to oil as the source of fuel.

Unfortunately, most hydrocarbon fuel oils contain impurities such as sulfur, vanadium and sodium which result in intolerably high corrosion and/or pollution rates when used in existing plants for high-temperature catalytic steam reforming of hydrocarbons.

Further, some of these fuels deposit slag and soot on heat transfer surfaces in the heatrecovery units making it necessary to periodically clean these surfaces.

Accordingly, it is important that the present invention provides a method for converting hydrocarbon fuel oils into a normally clean gasiform hydrocarbon fuel which is interchangeable with natural gas as fuel in existing reformer furnaces for the production of synthesis gas. Moreover, it will be apparent to those skilled in the art that the present invention provides an improved method for production of chemical products such as ammonia and methanol from synthesis gas with use of greatly reduced need for natural gas.

Referring to the drawing, liquid fuel oil is introduced into the system through line 1 together with non-oxidizing gas, through line 10 and/or line 7. Natural gas is passed through line 7. The fuel oil and nonoxidizing gas pass through heating coils 11 of a conventional vaporizer 12 where the outlet temperature is controlled within the range 3500 to 675"F. to give the desired proportion of vapor and liquid passing through line 2 to a conventional separator 13. Preferably, the liquid fuel oil fed has a gravity of 20 to 40 degrees A.P.I., and 25 to 75 percent by weight of this fuel oil is vaporized in vaporizer 12. Preferably, about 8 to 80 percent by weight of non-oxidizing gas based on the weight of the vaporized portion of the fuel oil is fed with the liquid fuel oil to the vaporizer.In separator 13, substantially all of the impurities present in the liquid fuel oil are contained in the liquid bottoms fraction. The substantially pure vapor fraction from separator 13 is passed through line 3 to heating coils 14 of vaporizer 12 where the vapor is superheated sufficiently to prevent downstream condensation. Desirably, the vapor is superheated to a temperature 1000 to 2000 F. greater than the temperature in separator 13.

Following superheating, the fuel vapor is passed through line 4 to reformer 15 where it is burned in existing conventional gas burners (not shown) with preheated air fed through line 16. The fuel vapor is burned without vanadium or sodium attack on the tubes of the high-temperature reformer, which tubes are constructed of stainless steel, preferably 25% Cr-20% Ni stainless steel, to resist attack by the contained synthesis gas. Reformer 15 is a conventional reformer for production of synthesis gas 25 by reacting a feed stock 24 consisting of purified natural gas and steam, at a temperature above about 1,200 F. in contact with a catalyst effective for conversion of the hydrocarbon and steam directly into carbon monoxide and hydrogen, said reaction being carried out in externally heated stainless steel tubes.

A portion of the clean vapor fuel from line 4 is passed through line 5 to vaporizer 12 where it is burned with air fed through line 17 in conventional gas burners (not shown). Hot clean combustion gas from vaporizer 12 is passed through line 6 to conventional heat recovery units 20 and 21 for heat recovery.

Following combustion of the vapor fuel in reformer 15, the combustion gas is passed through conventional heat recovery units 18, 19, 20, 21 without significant corrosive attack or deposition of slag and soot deposits. A portion of the recovered heat may be used for steam generation for use in the process. After passing through the heat recovery units, the combustion gas is vented to the atmosphere by means of blower 22 and stack 23. Vapor fuel from line 4 can also be fed through line 4a and burned with air fed through line 16a to fuel utility steam boilers (not shown).

When a portion of the fuel requirement is available as natural gas, the natural gas advantageously serves as the non-oxidising gas. It can be injected through line 7 into line 1 in place of all of the steam of water fed through line 10, in the process of our aforesaid prior British Patent Applications, thereby decreasing the temperature required for oil vaporization and contributing to the heating value of the vaporized fuel passing from separator 13 into line 3. When, as in a conventional process, the full fuel requirement is available as natural gas, the vaporizer 12 can be by-passed and full fuel requirement supplied through line 8 to line 4.

The impure bottoms fraction in line 9 from separator 13 can be used in power generating or other process units designed to handle such fuels with efficient pollution abatement.

The present process can be successfully operated utilizing fuel oil in units originally equipped with burners designed for natural gas fuel. This finding is especially important for reformers equipped with a multiplicity of burners where changing burners would entail extended interruption to operation and high equipment replacement costs. The present process can be operated without pollution problems utilizing fuel oils containing sulfur and other impurities which normally form pollutants during combustion.The present process can be operated without significant corrosion of reformer tubes, using fuel oils containing mineral impurities, specifically, vanadium and sodium, which would normally corrode materials of construction (stainless steel) used in reformers operating at or above 1,200 F. The present process can be successfully operated using fuel oils which if burned directly would cause slagging and soot deposition in the heat recovery sections of the reformer.

EXAMPLE The fuel oil used in this example is a No. 2 fuel oil having a gravity of 34 to 39 degrees A.P.I., containing trace amounts of vanadium and sodium and about 0.35 percent by weight of sulfur.

The test can be carried out in a multiunit fertilizer complex originally designed to burn natural gas fuel exclusively. In part, the test can be carried out in a unit for production of synthesis gas by reacting natural gas with steam at a temperature of 1,200 to 1,6000F in a reforming reaction in contact with a nickel oxide catalyst effective for conversion of the hydrocarbon and steam directly into carbon monoxide and steam under conditions such that the hydrocarbon is substantially completely converted with the steam. The reforming reaction is conducted in a conventional reformer in externally heated stainless steel (25% Cr-20% Ni) furnace tubes heated by means of burners equipped to burn a gasiform fuel.

Referring to the drawing, the liquid fuel oil is fed into the vaporizer 12 through line 1 at a rate of 1,750 pounds per minute. About 700 pounds per minute of natural gas is fed through line 7 and line 1 to vaporizer 12.

The vaporizer is heated by burning purified superheated overhead vapor from line 5. No steam is fed to vaporizer 12 through line 10.

The liquid-vapor oil stream exit vaporizer 12 is controlled at a temperature of about 390"F and pressure of 35 psig. The liquidvapor oil stream is fed to separator 13 through line 2. The bottoms from separator 13 consist of oil containing about 0.7 percent by weight of sulfur and substantially all of the mineral impurities originally present in the fuel oil supply. The bottoms are fed through line 9 to power units designed for such fuel. The purified vapor fraction from separator 13, substantially free from entrained particulate carbon, and containing about 0.8 lb. of natural gas per lb. of oil vapor, is passed through line 3 and heating coils 14 in vaporizer 12.The vapor is superheated in the heating coils to a temperature of 750--800"F to gilve purified superheated oil vapor and natural gas having a temperature of about 750"F, which is distributed as follows. A major proportion is passed through line 4 to reformer 15 where it is burnt in conventional burners designed to burn natural gas. A clear, colorless, flame is produced. A minor proportion is fed to utility steam boilers (not shown) not equipped with soot blowing or pollution abatement equipment. A small amount of the fuel gas is passed through line 5 to provide fuel for vaporizer 12, from which flue gas flows through line 6 to reformer heat recovery units 20 and 21.

WHAT WE CLAIM IS: 1. A process of producing a hot gas, which process comprises preparing a gasiform fuel by vaporizing a portion of a liquid hydrocarbon fuel oil having a gravity of 10 to 50 degrees A.P.I. at a temperature of 350 to 6750F in the presence of 5 to 90 /" by weight of a non-oxidizing inert gas (as hereinbefore defined), based on the weight of the vaporized portion of said hydrocarbon fuel oil, separating the resulting gasiform fuel from the liquid phase, and burning the gasiform fuel in a burner equipped to burn gasiform hydrocarbon fuel.

2. A process according to claim 1 wherein the portion of the liquid hydrocarbon fuel oil which is vaporized is at least 25% by weight, and the non-oxidizing inert gas is other than steam or a mixture of steam with natural gas.

3. A process according to claim 2 wherein 25 to 75% by weight of the liquid hydrocarbon fuel oil is vaporized.

4. A process according to claim 3 wherein 40 to 60 percent by weight of the liquid hydrocarbon fuel oil is vaporized.

5. A process according to any preceding claim, wherein the liquid hydrocarbon fuel oil has a gravity of 3040 degrees A.P.I.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. into line 3. When, as in a conventional process, the full fuel requirement is available as natural gas, the vaporizer 12 can be by-passed and full fuel requirement supplied through line 8 to line 4. The impure bottoms fraction in line 9 from separator 13 can be used in power generating or other process units designed to handle such fuels with efficient pollution abatement. The present process can be successfully operated utilizing fuel oil in units originally equipped with burners designed for natural gas fuel. This finding is especially important for reformers equipped with a multiplicity of burners where changing burners would entail extended interruption to operation and high equipment replacement costs. The present process can be operated without pollution problems utilizing fuel oils containing sulfur and other impurities which normally form pollutants during combustion.The present process can be operated without significant corrosion of reformer tubes, using fuel oils containing mineral impurities, specifically, vanadium and sodium, which would normally corrode materials of construction (stainless steel) used in reformers operating at or above 1,200 F. The present process can be successfully operated using fuel oils which if burned directly would cause slagging and soot deposition in the heat recovery sections of the reformer. EXAMPLE The fuel oil used in this example is a No. 2 fuel oil having a gravity of 34 to 39 degrees A.P.I., containing trace amounts of vanadium and sodium and about 0.35 percent by weight of sulfur. The test can be carried out in a multiunit fertilizer complex originally designed to burn natural gas fuel exclusively. In part, the test can be carried out in a unit for production of synthesis gas by reacting natural gas with steam at a temperature of 1,200 to 1,6000F in a reforming reaction in contact with a nickel oxide catalyst effective for conversion of the hydrocarbon and steam directly into carbon monoxide and steam under conditions such that the hydrocarbon is substantially completely converted with the steam. The reforming reaction is conducted in a conventional reformer in externally heated stainless steel (25% Cr-20% Ni) furnace tubes heated by means of burners equipped to burn a gasiform fuel. Referring to the drawing, the liquid fuel oil is fed into the vaporizer 12 through line 1 at a rate of 1,750 pounds per minute. About 700 pounds per minute of natural gas is fed through line 7 and line 1 to vaporizer 12. The vaporizer is heated by burning purified superheated overhead vapor from line 5. No steam is fed to vaporizer 12 through line 10. The liquid-vapor oil stream exit vaporizer 12 is controlled at a temperature of about 390"F and pressure of 35 psig. The liquidvapor oil stream is fed to separator 13 through line 2. The bottoms from separator 13 consist of oil containing about 0.7 percent by weight of sulfur and substantially all of the mineral impurities originally present in the fuel oil supply. The bottoms are fed through line 9 to power units designed for such fuel. The purified vapor fraction from separator 13, substantially free from entrained particulate carbon, and containing about 0.8 lb. of natural gas per lb. of oil vapor, is passed through line 3 and heating coils 14 in vaporizer 12.The vapor is superheated in the heating coils to a temperature of 750--800"F to gilve purified superheated oil vapor and natural gas having a temperature of about 750"F, which is distributed as follows. A major proportion is passed through line 4 to reformer 15 where it is burnt in conventional burners designed to burn natural gas. A clear, colorless, flame is produced. A minor proportion is fed to utility steam boilers (not shown) not equipped with soot blowing or pollution abatement equipment. A small amount of the fuel gas is passed through line 5 to provide fuel for vaporizer 12, from which flue gas flows through line 6 to reformer heat recovery units 20 and 21. WHAT WE CLAIM IS:

1. A process of producing a hot gas, which process comprises preparing a gasiform fuel by vaporizing a portion of a liquid hydrocarbon fuel oil having a gravity of 10 to 50 degrees A.P.I. at a temperature of 350 to 6750F in the presence of 5 to 90 /" by weight of a non-oxidizing inert gas (as hereinbefore defined), based on the weight of the vaporized portion of said hydrocarbon fuel oil, separating the resulting gasiform fuel from the liquid phase, and burning the gasiform fuel in a burner equipped to burn gasiform hydrocarbon fuel.

6. A process according to any preceding

claim, wherein the hydrocarbon fuel oil is vaporized in the presence of 8-30 percent by weight of the non-oxidizing gas, based on the weight of the vaporized portion of said hydrocarbon.

7. A process according to any preceding claim wherein the gasiform hydrocarbon fuel is superheated to a temperature effective to prevent condensation thereof before it is burned.

8. A process according to any preceding claim wherein the gasiform hydrocarbon fuel is burnt in a burner of the kind which is equipped to burn natural gas as fuel.

9. A process according to any preceding claim wherein the hot gas produced is used to heat a furnace.

10. A process according to any preceding claim carried out in apparatus constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

11. A process according to any preceding claim, wherein the non-oxidizing gas is natural gas.

12. A process according to claim 1, substantially as described in the Example.

13. A process according to any one of claims 1 to 10, wherein the non-oxidizing gas is ammonia synthesis purge gas or a mixture thereof with steam.

14. Hot gas produced by a process claimed in any one of claims 1 to 12.

15. Hot gas produced by a process claimed in claim 13.

16. A process for the production of synthesis gas, which comprises reacting a gasiform hydrocarbon with steam at a temperature of at least 12000F in a reforming reaction for conversion of the hydrocarbon and steam directly into carbon monoxide and hydrogen, and supplying heat to said reforming reaction from hot gas claimed in claim 14 or 15.

17. A process according to claim 16, wherein the hot gas from the burner is contacted with a stainless steel furnace in heat-supply relationship to the reforming reaction.